Heated plate unit for defrosting systems



Feb. 8, 1955 H. w. KLElsr 2,701,455

HEATED PLATE UNIT FOR DEFRosTING SYSTEMS Filed July 23, 1952 A 3 Sheets-Sheet l max ms l` K 2902 (1km .QQ SS mi N .NSN

Feb. 8, 1955 H. w. KLElsT 2,701,455

HEATED PLATE UNIT FOR DEF'ROSTING SYSTEMS Filed July 23, 1952 3 Sheets-Sheet 2 L JQ /2 fg 14 l 4 7 5 .Iz/forays.

Feb. 8, 1955 H. W. KLEIST HEATED PLATE UNIT FOR DEFROSTING SYSTEMS Filed July 25, 1952 3 Sheets-Sheet 3 fraz/enfer /f/za?? Wff/ealsf y MM L CM1EIL United lStates Patent() HEATED PLATE UNIT FOR DEFROSTING SYSTEMS Application July 23, 1952, Serial No. 300,376

3 (Claims. (Cll 621`26) :My invention relates to an improvement in automatic defrosting systemsy and in heat interchangers for use therewitli.- One object isrito provide such a system in which aheat interchanger is positioned to vaporize the volatile refrigerant which has been delivered to an evaporator or evapprators in the form of hot gas, to defrost the evaporators, 'the heat interchanger being located in the suction line between the evaporator or evaporators and the compressor. i

Another object is to provide plates which may be used in such a system, to provide a plane-sided plate, which is etlcient in use and simple to manufacture.

Another object is to provide an improved plate in which a pressure dilerential between the interior and the exterior of the plate is employed to hold parts of the plate in heat exchange relationship.

Other objects will appear from time to time in the course of the specification and claims.

The present application is a continuation-impart of my copending application Serial No. 79,274, filed March 2, 1949, now Patent No. 2,638,754, issued May 19, 1953, for Stamped Plates.

I illustrate my invention more or less diagrammatically in the accompanying drawings wherein:

Figure 1 is a diagrammatic illustration of my automatic defrosting system;

Figure 2 is a plan view of a heat interchanger;

Figure 3 is a side view of the structure of Figure 2;

Figure 4 is a section, on an enlarged scale, on the line 4 4 of Figure 3, with parts broken away;

Figure 5 is a section similar to Figure 4, through a variant form of unit;

Figure 6 is a section on the line 6--6 of Figure 5;

Figure 7 is a plan view, with parts broken away, of another form of heat interchanger;

Figure 8 is a section on the line 8-8 of Figure 7; and

Figure 9 is a plan view, with parts broken away, of a further form of heat interchanger.

Like parts are indicated by like symbols throughout the specification and drawings.

Referring, rst, to Figure l, 100 illustrates, more or less diagrammatically,v a compressor which may, for

example, be driven byfany suitable motor 101 through a belt 102. 103 indicates a hot gas line or discharge pipe from the pressure side of the compressor 100, which may extend to a suitable condenser structure 104 and therethrough to a suitable receiver 105. 106 is a duct extending to any suitable evaporator structure 107. 108 is a liquid indicator, 109 a suitable dryer, and 110 any suitable expansion valve which may, for example, be controlled by the bulb 111 on the return duct or pipe-112 extendingl from the evaporator.

A generally indicates a heat'interchanger, various forms of which are illustrated in Figures 2 and following. v In Figure 1 it is illustrated as having an electric or resistance heating unit 115 and a coil 116 in communication with the return pipe 112. It will be understood that, through an auxiliary receiver 117, the refrigerant continues.

through the iinal return duct section 118 to the suction side of the compressor 100. 117a is any suitable oil return for the auxiliary receiver. yIn the form of my systern shown in Figure l, B indicates any suitable timing device. Its control means do not, of themselves, form part of the present invention, but it .will be understood that either by manual or by automatic control the timing device may be actuated, and when actuated it controls the below-described elements.

2,701,455 Patented Feb. 8, 1955 120 indicates a valve, which may be a solenoid valve, actuated by any suitable coil 121 controlled by the timmg de vice B. When the timing device is actuated the solenoid valve, which is normally in closed position, opens, and permits hot gas to flow along the by-pass 103a, through the valve 120 to the evaporator 117, at a point beyond the expansion valve 110. 122 indicates any suitable power circuit in which the timing device B is ineluded. 123 indicates any suitable fanwhich may be actuated, preferably, in synchronism with the actuation of the valvel20, to direct air upon the exterior of the evaporator 107 and to assist in the defrosting process.

It will understood that, in the use of the system dlagrammatically shown in Figure 1, many changes in the arrangement and details of parts and elements may be employed. What I consider essential is that l provide, in the return trom the evaporator to the suction side of the compressor, some means for re-evaporating the hot gas which has been condensed in the evaporator 107 during the defrosting cycle. I illustrate, diagrammatically, in Figure 1,a heat interchanger which includes an electric heating element and a refrigerant receiving coil 116. It is preferable, although not necessary, to employ, within the unit A, a heat absorption substance, which may, for example, be a liquid, such as glycerine, alcohol and water, or the like, When such a liquid is employed, the coil 115, when put in circuit with a source of electricity, serves to heat the body of liquid, the heat so provided being available to vaporize the condensed volume of the volatile refrigerant owing from the evaporator during defrostmg.' It will be understood that I may employ a wide variety of heaty interchangers, and may employ electricity as a heating means, or any suitable liquid or gas, heated in any suitable manner.

Figures 2 and following show various types of units or heat interchangers which may be employed. I prefer to employ plates as compact elements having sound structural characteristics. Referring, tirst, to the form of Figures 2 to 4, 1 generally indicates a plate side wall of sheet metal, shown as plane from edge to edge. 2 generally indicates an intermediate wall of sheet metal which is shown as p ressed into proper shape to deline, with the wall 1, a refrigerant coil or passage, generally indicated as A. The member 2 may havev plane edge portions 3 and intermediate plane portions 4, all of which abut against the inner surface of the side wall 1. They are appropriately secured together. They may, for example, be initially spotwelded, and thereafter seam-welded, in such fashion that the two walls together deiine an evaporator passage or coil A which is substantially gas-tight from the end 5 to the end 6.

The coil proper is shown as formed by bowed or offset wall portions 7 of the wall 2, which may be of any suitable contour, and which are herein shown as generally rounded and so formed as to be readily made by a pressing operation. It will be understood that the ends of the evaporator passage A, as at 5 and 6, are connected to suitable ducts or tubes 5a and 6a, whichv may constitute, respectively, inlet and outlet passages for the volatile refrigerant delivered by the pipe 112 of Figure 1 and received by the pipe 118. If the volatile refrigerant is admltted in liquid or partially liquid form through the pipe 5a, it evaporates in the coil space A, and the evaporated refrigerant is discharged along the tube 6a to the pipe 118. The space between the side walls l and 10 may be filled, or partly filled, with any suitable heat absorbent liquid, and this liquid may be heated by any suitabe gesistance, such as is indicated at 115a in Figures 2 an In designing and using such plates I ind it highly desirable to have the sides of the plates plane, and, in most instances, parallel. Such plane-surfaced plates are applicable to a wide variety of uses, in addition to their use as heat interchangers. They may, for example, be employed directly as evaporating plates in which the volatile refrigerant is normally evaporated, in which event the liquid employed can be the usual eutectic. lt is frequently important to nest such plates in narrow spaces, the individual plates having adjacent walls separated by air spaces, as in air conditioning units and the like. or in refrigerating units for cooling air or liquids.

having wi In that event, it is important to have the outer surfaces of the plates plane on both sides. I employ a'second outside wall 10, shown as plane throughout most of its I side wall portions 11 and edge be secured to corresponding p orto form a housing surface, but as having flanges 12 which may tions of the edge of the side wall 1, or plate which is gas-tight. l

It will be understood that I may form a plate otherwise than by the particular shape of edge anges herein shown, but the structure shown in the drawings is practical and satisfactory. The space between the side wall 10 and the intermediate wall 2, which I indicate as B, may receive an eutectic, or may bek air-filled, or may receive glycerine, Prestone, or the like, whenvthe plate i" being used as a heat interchanger in such a system, as is shown in Figure 1. In any event, I refe i partially to exhaust the space B. This may be one in any suitable fashion, but I may, for example, en iploy any suitable pump, not herein shown, to exhaust air through the fitting generally indicated as 14. This fitting may have a duct 15 through which air may bedrawn from the interior of the plate. When a suitable pressure dif,- ferential has been obtained the operation of the pump may be terminated. When this takes place the outside air pressure urges the locking ball 16 against the inlet end of the duct or passage 15. Thereafter, any suitable sealing material may be positioned about the ball 16, if desired, and a tight closure plug 17 may be inserted. As a result, the pressure differential may be permanently, or substantially permanently, maintained, with the outside excess pressure elective to urge the side wall 10 trmly against the crests 7a of the coil structure 2. Thus an adequate heat exchange relationship is maintained between the side plate 10 and the evaporating refrigerant in the coil space A. And the plate is maintained at and firm, with the side walls 1 and 10 plane, and parallel in relation to each other. If desired, the same tting may be employed for the initial insertion or the addition of liquid to the interior of the plate.

Whereas a small volume of liquid may be use in the form of Figures 2 to 4, under normal circumstances, where an eutectic or other liquid is used, it is advantageous to provide a relatively large body of liquid. In such event, the form of Figures and 6 may be employed, in which the plate side wall 20 is provided with circumferential walls or flanges 21 which are substantially deeper or broader than the walls 11 of Figure 4. Since this positions the plane portion of the side wall 20 remotely from the pressed coil structure of the intermediate wall 2, I provide a plurality of vanes 22 which may be connected by any suitable cross supports, spacing rods or the like 23. to abut against the inner surface of the side wall 20, when that side wall is inwardly drawn by the above described pressure differential. The vanes 22, at their opposite edges, may engage the opposed surface of the intermediate plate 2. It will be understood, however, that whereas it is advantageous to form the vane edges 25 to conform generally to the coil structure of the intermediate wall 2, it is not necessary to employ micrometric accuracy. The result of the employment of the above described pressure dilerential is to cause the atmosphere, operating on the exterior surfaces of the side walls 1 and 20, to hold the edges of the vanes 22 in adequate heat exchange relation with the wall 20 on the one hand and with the wall 2 on the other. In order to permit distribution of and expansion of the eutectic, I provide any suitable apertures or broken away portions in the vanes 22. I illustrate, for, example, apertures 26. I illustrate a heating unit l15b, illustratively shown as a suitable resistance. Under some circumstances, as when the plate is used as an ordinary evaporator plate for refrigeration, with no defrosting provision, the heating unit or units .may be omitted. I illustrate, for example, in the form ofFigures 2 to 4, inclusive, a heating resistance l15a which, as a matter of convenience, is shown as including a duct 50 thin it a suitable resistance wire 51 and any suitable insulation 52. This duct 50 may, at the same time, have an outside diameter equal to the space between the plate walls 1 and 10, so that the heating member is in good heat transfer relation with both sides of the plate. It will be understood; of course, that the details of the resistance unit do not of themselves form part of the gieesent invention, and that any suitable resistance may employed. In Figure 2, I illustrate the resistance unit The vanes 22 have straight edges 24 adapted 4 as positioned between spaced lengths of the evaporator coil 7. 53 and 54 indicate any suitable conductive connections which will be understood to extend to any suitable source of current.

In the form of Figures 5 and 6, the resistance 115b is only diagrammatically illustrated, it being understood that any suitable conductive connection may be provided therefor, and that it may be placed or supported in any suitable manner.

Referring to Figures 7 and 8, I illustrate a form of plate in which the side walls 70 and 71 are sealed around their edges and connected by peripheral portions 72. A refrigerant coil 73 occupies part of the space between the two plate side walls 70 and 71, and the pressure diterential., as above described, obtained by the use of the litting 14, causes the outside atmospheric pressure to hold the'walls 70 and 71 in snug and properheat transfer relationship with the coil 73. At the same time, I provide a heating fluid coil portion 74 which is shown as surrounding the coil 73, within the edgs of the plate, The coil 73 has its own inletand outlet portions 73a. while the coil 74 has its own individual inlet and outlet portions 74g. Any suitable liquid may be admitted through the fitting 14, and may partially or substantially entirely ll Ellie space about the coils and within the plate walls 70 and Figure 9 illustrates a similar plate, with the dierence that in the place of the heating coil 74 a resistance 75 is employed, which preferably, but not necessarily, includes an outer conductive housing or shell 76 of the same vgauge as the refrigerant coil 73. Thus, in both forms, the

showing.

The use and'operation of the invention are as follows:

.I illustrate, in Figure l, a more or less schematic or diagrammatic showing of an automatic defrosting system. In Figures 2 and following I have illustrated several forms of heat interchanger. These may advantageously be plates adaptable for other uses. For example, all the forms of plates herein described and shown may be employed not only as heat interchangers in a system such as is shown in Figure 1. but as evaporators for use in refrigeration. In that event, if the heating elements are employed the evaporators may be directly defrosted by application of heat. If such units are to be employed merely as evaporators, and the application of heat directly to the plates is not desired, the heating elements may be omitted.

I illustrate an automatic defrosting system of maximum simplicity and heat interchanger units which are simple, compact, strong, ca sily installed, and easily shipped. ing flat or plane-sided, they are easily cleaned. When they have to be defrosted they defrost easily, and the frost sloughs otf or can easily be cleaned or scraped olf All of the units shown herein may be employed as evaporators, in which event they may be defrosted by direct application of heat to the individual evaporators. They are also adapted for use as heat interchangers in defrosting systems.

Where the unit is being used simply as a truck plate or as a refrigerating plate, then a eutectic may be employed which freezes at some predetermined. desirable temperature. The structure is adaptable and useful. without change. either as an evaporator or as a vaporizer for the specific use above described. It will be understood, also, that where the unit is usedas a heat interchanger any suitable material may be employed which has suitable heat absorbing or heat retaining c teristics.

I claim: y

l. In a vacuum type plate, two outer plate walls having generally parallel plane surfaced sides and conn g edge portions, said edge portions being secured together in gas-tight relationship, with said plane surfaced sides spaced part, an intermediate sheet metal wall in the space between said plate walls, forming, with one of said plate walls, a

I therefore wish my description and coil space, the opposed portions of said intermediate sheet metal wall and said last mentioned plate wall being secured together` in gas-tight relationship, a tubular element posi tioned between said intermediate sheet metal wall and the opposite plate wall, a resistance heater therewithin, heat storage means surrounding and in heat conductive relationship with said tubular element, and inlet and outlet ducts or the coil formed by said walls.

2. The structure of claim 1, characterized in that the tubular element abuts and is in heat exchange relation with the intermediate sheet metal 'wall and one of the outer plate walls.

3. The structure of claim l, characterizedA by and incluclingv spacing means between the intermediate sheet metal wall and the opposite outer plate wall, the tubular l5 element with the resistance heater being supported by said spacing means.

References Cited in the tile of this patent UNITED STATES PATENTS 2,126,285 Schaaf Aug. 9, 1938 2,217,702 Kleist Oct. 15, 1940 2,281,770 l-Ioesel` May 5, 1942 2,440,146 Kramer Apr. 20, 1948 2,487,674 ott Nov. 8, 1949 2,526,319 Maseritz Oct. 17, 1950 2,611,587 Boling Sept. 23, 1952 2,637,983 Malkoff et al May 12, 1953 2,638,754

Kleist May 19, 1953 

